JP2014178074A - End-stop type electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end-stop type electric water heater capable of discharging water in a hot water storage tank through an easy operation as required amount only when a water supplying to the hot water storage tank is stopped.SOLUTION: This invention relates to an end-stop type electric water heater 1 in which a flow passage for water fed from a hot water storage tank 5 is opened or closed by a faucet 3 at a lower position than that of the hot water storage tank 5. The end-stop type electric water heater 1 comprises a water supply pipe 11 for connecting a water supply port 14 arranged in the casing 6 with a bottom part 5a of the hot water tank 5 so as to supply water to the hot water storage tank 5, a check valve 16 arranged at the water supplying pipe 11, a tap pipe 12 for connecting a top surface part 5c of the hot water storage tank 5 with a tap port 18 arranged at the casing 6 so as to feed the water in the hot water storage tank 5 to the tap port 18, a water discharging pipe 21 branched from a downstream side lower than the check valve 16 in the water supply pipe 11 and connected to a water discharging port 22, a water discharging pipe 13 for connecting the hot water storage tank 5 with a water discharging port 19 communicated with surrounding atmosphere, and surrounding atmosphere intake means connected to the hot water storage tank 5 to feed surrounding atmosphere into the hot water storage tank 5 when a pressure within the hot water storage tank 5 is lower than the surrounding atmospheric pressure.

Description

  The present invention relates to a first-stop electric water heater that closes a flow path and stops water on the downstream side of a hot water storage tank containing a heating means. Specifically, the present invention relates to a front-end electric water heater that is suitably used as a wall-mounted electric water heater provided on a wall above a faucet installed on a kitchen sink or the like.

  2. Description of the Related Art Conventionally, there is a hot water storage type electric water heater provided with a hot water storage tank incorporating heating means such as an electric heater as an electric water heater that heats water with electric power. A hot water storage type electric water heater supplies hot water in a hot water storage tank to a faucet serving as a water discharge unit installed in a kitchen sink or a washbasin in a washroom. In a hot water storage type electric water heater, water supplied from a water supply source such as a water pipe reaches a hot water storage tank through a water supply pipe from a water supply port provided in a casing that houses the hot water storage tank. The water supplied to the hot water storage tank is heated by heating means such as an electric heater provided in the hot water storage tank to become hot water. Hot water in the hot water storage tank is supplied to the faucet through the hot water outlet pipe.

  In the faucet supplied with hot water from the hot water storage tank, the hot water from the hot water storage tank and a part of the water supplied from the water supply source are mixed through the mixing valve. Here, the water mixed with hot water by the mixing valve is supplied by a bypass pipe branched from the water supply pipe upstream of the water supply port of the casing, that is, before reaching the casing, in the water supply pipe through which water from the water supply source passes. . And the mixed water obtained by the mixing of the hot water with a mixing valve is discharged from the spout of a faucet.

  Such a hot water storage type electric water heater has a drain stop valve on the bottom side of the hot water storage tank in order to drain the water in the hot water storage tank when cleaning the hot water storage tank or replacing the water in the hot water storage tank. There exists a thing of the structure provided (for example, refer patent document 1). In such a configuration, by opening the drain stop cock by operating the valve for opening and closing, the water in the hot water storage tank can be discharged and the hot water storage tank can be emptied.

  Moreover, as a structure of a hot water storage type electric water heater, there exists what is called a ball tap type structure like the electric water heater of patent document 1, for example. A ball tap type electric water heater is provided with a ball tap that opens and closes a water supply path to the hot water storage tank in conjunction with the movement of a floating ball floating on the water in the hot water storage tank. That is, when the water level in the hot water storage tank is lowered from a predetermined position, the water supply path to the hot water storage tank is opened by the ball tap and water is supplied into the hot water storage tank, and when the water level in the hot water storage tank rises from the predetermined position, The water supply path to the hot water storage tank is closed by the ball tap, and the water supply to the hot water storage tank is stopped. When hot water in the hot water storage tank is supplied, stored hot water above the upper end opening position of the hot water pipe arranged in the vertical direction so that the inside and outside of the hot water tank communicate with each other is discharged from the hot water pipe by gravity. Is done.

  In such a ball tap type electric water heater, the water pressure of the hot water discharged from the tapping pipe fluctuates depending on the water level in the hot water storage tank. For example, when washing in a kitchen sink, it is sufficient. Water pressure may not be obtained. In this respect, according to the so-called first stop type electric water heater, it becomes easy to obtain a sufficient water pressure for the hot water discharged from the hot water discharge pipe. The front stop type electric water heater is an electric water heater configured to stop water by closing a flow path on the downstream side of the hot water storage tank. In the first-stop type electric water heater, water is discharged from the hot water storage tank through the hot water discharge pipe by the pushing action using the water supply pressure (tap pressure, etc.) from the water supply source, so the hot water discharged from the hot water discharge pipe is relatively high. Water pressure is obtained.

JP 2004-77066 A

  In the hot water storage type electric water heater as described above, even when the water supply from the water supply source is inadvertently stopped, such as in the event of unexpected water outages or disasters, There is an advantage that the stored water in the hot water storage tank can be used by the drain stop cock for draining water. However, the conventional hot water storage type electric water heater has the following problems when the water in the hot water storage tank is used when the water supply is stopped.

  Operations that require operation of the drain stop cock, such as cleaning the hot water tank or replacing the water in the hot water tank, are not frequently performed, so opening and closing the drain stop cock is difficult to remember. Each time the drain stop cock is operated, it tends to be an operation with reference to the manual. For this reason, there is a problem that it is necessary to perform complicated and unfamiliar work when using water in the hot water storage tank at the time of unexpected water outage or inadvertent water supply stoppage at the time of disaster, etc. .

  In addition, with regard to the work for removing water from the hot water storage tank, in the case of normal work performed when cleaning the hot water storage tank, etc., the hot water in the hot water storage tank is replaced with water, and then the drainage from the drain stop valve is drained. However, in the event of an unexpected water outage or inadvertent water supply stoppage such as a disaster, it may be necessary to remove the water in the hot water storage tank before the temperature of the water in the hot water storage tank drops. In such a case, even if the drain stop valve can be opened, the drain stop cock is heated by the hot water discharged from the hot water storage tank, making it difficult to touch the drain stop cock. There is a possibility that the valve cannot be closed. Also, if you try to close the drain stop cock, you may be uncomfortable with unexpectedly hot water.

  The present invention has been made in view of the circumstances as described above, and is a first-stop electric type capable of discharging water in a hot water storage tank by an amount required by an easy operation when water supply to the hot water storage tank is stopped. The purpose is to provide a water heater.

  A first-stop electric water heater according to a first aspect of the present invention stores a hot water storage tank provided with a heating means for heating water in a casing, and a flow path of water from the hot water storage tank is outside the casing. A hot water heater that is opened and closed by a faucet provided at a position lower than the bottom of the hot water storage tank, wherein the hot water storage tank is connected to a water supply port provided in the casing and the bottom of the hot water storage tank. A water supply pipe for supplying water, a check valve provided in the water supply pipe, a top surface portion of the hot water storage tank, and a hot water outlet provided in the casing and communicating with the water tap, A hot water pipe that leads the water to the hot water outlet, a water outlet pipe that branches from the downstream side of the check valve of the water supply pipe, and that is connected to the water outlet that communicates with the faucet, the hot water storage tank and the atmosphere Drain connected to a drain port communicating with A tube, connected to the hot water storage tank, when the pressure of the hot water storage tank is less than atmospheric pressure, is characterized in that and a air introducing means for introducing air into the hot water storage tank. According to the first-stop type electric water heater having such a configuration, when the water supply to the hot water storage tank is stopped, the water in the hot water storage tank can be discharged by an easy operation by an amount required.

  The first-stop electric water heater according to the second aspect of the present invention is the first-stop electric water heater according to the first aspect, wherein the air introduction means is provided in the drain pipe, and the hot water storage tank It is a negative pressure valve that closes when the internal pressure is equal to or higher than the atmospheric pressure and opens when the internal pressure of the hot water storage tank is lower than the atmospheric pressure. According to the front-stop type electric water heater having such a configuration, water discharge in the hot water storage tank is performed by the structure including the negative pressure valve when the water supply is stopped. A state where water can be taken out can be automatically realized.

  A first-stop electric water heater according to a third aspect of the present invention is the first-stop electric water heater according to the first aspect, and is provided in the drain pipe, and the pressure in the hot water storage tank is predetermined. A relief valve that opens and closes according to the pressure in the hot water storage tank, which is closed when the pressure is less than the pressure and opens when the pressure in the hot water storage tank is equal to or higher than the predetermined pressure; Is a first state in which an opening / closing operation is performed according to the pressure in the hot water storage tank, and a second state in which the valve is opened regardless of the pressure in the hot water storage tank The air introduction means includes the drain pipe and the relief valve in the second state. According to the first-stop type electric water heater having such a configuration, when the water in the hot water storage tank is used when the water supply is stopped, the structure of the relief valve is used. Therefore, the hot water type electric water heater is generally used. The existing configuration of the relief valve that is provided can be used, the configuration can be simplified, and the water in the hot water storage tank can be used by the operation of the faucet by manual operation when the water supply is stopped Can be definitely obtained.

  According to the present invention, when the water supply to the hot water storage tank is stopped, the water in the hot water storage tank can be discharged by an easy operation by the required amount.

The external view which shows the structure of the tip-stop type electric water heater which concerns on one Embodiment of this invention. The figure which shows the structure of the tip-stop type electric water heater which concerns on 1st Embodiment of this invention. The figure which shows the structure of the negative pressure valve which concerns on 1st Embodiment of this invention. The figure which shows the structure of the tip-stop type electric water heater which concerns on 2nd Embodiment of this invention. The figure which shows the valve structure which concerns on 2nd Embodiment of this invention. The figure which shows the structure of the tip-stop type electric water heater which concerns on 3rd Embodiment of this invention. The figure which shows the valve structure which concerns on 3rd Embodiment of this invention. The figure which shows the valve structure which concerns on 3rd Embodiment of this invention.

  The present invention provides a front-end type electric water heater having a hot water storage tank with a built-in heating means, by providing a structure for introducing the atmosphere into the hot water storage tank when the pressure in the hot water storage tank is less than atmospheric pressure, Even when the water supply from the water supply source to the hot water storage tank is stopped, the water in the hot water storage tank can be used by a normal water discharge operation. Embodiments of the present invention will be described below.

[First Embodiment]
A first embodiment of the present invention will be described. As shown in FIG. 1, a first-stop electric water heater (hereinafter simply referred to as “electric water heater”) 1 of the present embodiment is relatively small as an electric water heater, for example, in a hot water supply room of an office. This is a wall-mounted electric water heater installed in a state of being hung on a wall 4 above a faucet 3 provided for the sink 2. In addition, as an electric water heater which concerns on this embodiment, it may be provided above the faucet provided, for example with respect to the washbasin of a washroom.

  The electric water heater 1 of this embodiment is a hot water storage type electric water heater provided with a hot water storage tank 5 incorporating heating means. That is, the electric water heater 1 supplies hot water in the hot water storage tank 5 to a faucet 3 as a water discharge portion provided for the sink 2. The hot water storage tank 5 is accommodated in a rectangular parallelepiped casing 6. That is, the electric water heater 1 has a casing 6 that houses the hot water storage tank 5, and the casing 6 is attached to the wall 4 together with the casing 6. With respect to the electric water heater 1 installed above the faucet 3 provided for the sink 2 as described above, the faucet 3 is provided at a position lower than the bottom of the hot water storage tank 5 outside the casing 6. It will be.

  The electric water heater 1 is supplied with water by a water supply pipe 7 from a water supply source such as a water pipe. Water supplied to the electric water heater 1 from the water supply pipe 7 reaches the hot water storage tank 5 through a water supply pipe (see FIG. 2, water supply pipe 11) arranged in the casing 6. In the hot water storage tank 5, the supplied water is warmed by the heating means. Hot water in the hot water storage tank 5 is supplied to the faucet 3 by a hot water discharge pipe 8 through a hot water discharge pipe (see FIG. 2, hot water discharge pipe 12) arranged in the casing 6. Further, water is supplied to the faucet 3 through a water discharge pipe 9 that constitutes a bypass path that branches off from a water supply path from a water supply source to the hot water storage tank 5. A water supply pipe 7 from the water supply source to the electric water heater 1 and a hot water supply pipe 8 and a water discharge pipe 9 from the electric water heater 1 to the faucet 3 are arranged on the back side of the wall 4.

  The faucet 3 to which hot water from the hot water discharge pipe 8 and water from the water discharge pipe 9 are supplied has a mixing valve for mixing the supplied hot water and water. The mixing valve is built in the housing 3 a constituting the water faucet 3. The mixed water obtained by mixing hot water with the mixing valve of the faucet 3 is discharged from the water outlet of the faucet 3.

  As shown in FIG. 1, the faucet 3 includes a hot water tap 3b that constitutes a hot water spout mainly used for drinks, and a mixing spout that constitutes a mixed water spout mainly used for washing. 3c. The hot water tap 3b and the mixing tap 3c are extended from the lower surface side of the housing 3a. An operation handle 3d for adjusting the amount and temperature of water discharged from the water outlet of the mixing plug 3c is provided on the upper surface side of the housing 3a. In the hot water tap 3b, an opening / closing handle 3e for opening and closing the hot water tap 3b is provided at a position near the water outlet.

  As described above, the electric water heater 1 of the present embodiment employs a first-stop type configuration in which the faucet 3 is disposed as a water stop portion that closes the flow path and stops water on the downstream side of the hot water storage tank 5. For this reason, in the electric water heater 1, water is discharged from the hot water storage tank 5 through the hot water discharge pipe 8 by the pushing action utilizing the water supply pressure (tap pressure or the like) from the water supply source. Therefore, in the electric water heater 1, a relatively high water pressure can be obtained for hot water discharged from the hot water discharge pipe 8 as compared with the conventional ball tap type configuration. In such a first-stop type configuration, the hot water storage tank 5 is a sealed tank.

  As described above, the electric water heater 1 of the present embodiment stores the hot water storage tank 5 provided with heating means for heating water in the casing 6, and the flow path of water from the hot water storage tank 5 is outside the casing 6. It has a first-stop type structure that is opened and closed by a faucet 3 provided at a position lower than the hot water storage tank 5. Hereinafter, the electric water heater 1 of this embodiment is demonstrated in detail using FIG.

  As shown in FIG. 2, the electric water heater 1 of this embodiment includes a hot water storage tank 5 housed in a casing 6. The hot water storage tank 5 stores hot water supplied to the faucet 3. The hot water storage tank 5 has a heater 5b as heating means. The heater 5b is an electric heater that generates heat by electric power, and warms the water in the hot water storage tank 5 by a heating action when energized. The heater 5 b is provided in the lower part in the hot water storage tank 5. The capacity of the hot water storage tank 5 is, for example, about 12 to 30 liters.

  The electric water heater 1 includes a water supply pipe 11 for supplying water to the hot water storage tank 5, a hot water discharge pipe 12 for discharging water (hot water) in the hot water storage tank 5, and a volume expansion of water in the hot water storage tank 5 having a closed structure as described above. And a drain pipe 13 for discharging water overflowing from the hot water storage tank 5.

  The water supply pipe 11 is piped in the casing 6, and connects the water supply port 14 provided in the casing 6 and the bottom 5 a of the hot water storage tank 5. That is, one end (upstream end) of the water supply pipe 11 is connected to the water supply port 14, and the other end (downstream end) of the water supply pipe 11 is connected to the bottom 5 a that is the lower surface of the hot water storage tank 5. Then, it communicates with the hot water storage tank 5. Thereby, the water supply pipe | tube 11 comprises the water supply path which supplies water to the hot water storage tank 5 from the water supply source with the water supply piping 7 which supplies the water with respect to the electric water heater 1 from a water supply source. The water supply port 14 is provided at the bottom 6 a of the casing 6 having a rectangular parallelepiped outer shape, and receives a connection at the downstream end of the water supply pipe 7. That is, the water supply port 14 constitutes a connection portion between the water supply pipe 7 outside the casing 6 and the water supply pipe 11 inside the casing 6 in the water supply path from the water supply source to the hot water storage tank 5.

  The water supply pipe 11 disposed in the casing 6 is provided with a valve unit 15 including a check valve 16 and a pressure reducing valve 17. In the present embodiment, a check valve 16 is provided on the upstream side of the pressure reducing valve 17. The check valve 16 prevents the flow of water supply from the water supply source to the hot water storage tank 5 from flowing in the reverse direction. The pressure reducing valve 17 has a predetermined pressure (hereinafter referred to as “tank pressure”) in the hot-water tank 5 because of its relationship with safety standards, the strength of the hot water tank 5, etc. For example, the water supply pressure from the water supply source (such as tap water pressure) is reduced so as to be maintained at 0.08 MPa or less. As described above, the electric water heater 1 includes the check valve 16 provided in the water supply pipe 11.

  The hot water discharge pipe 12 is piped in the casing 6, and connects the top surface portion 5 c of the hot water storage tank 5 and the hot water outlet 18 provided in the casing 6 and communicating with the faucet 3. That is, one end (upstream end portion) of the hot water discharge pipe 12 is connected to the top surface portion 5c which is the upper surface portion of the hot water storage tank 5 and communicates with the inside of the hot water storage tank 5, and the other end (downstream end of the hot water discharge pipe 12). Part) is connected to the tap 18. As described above, the hot water discharge pipe 12 is a pipe that guides the water (hot water) in the hot water storage tank 5 to the hot water outlet 18. As a result, the hot water discharge pipe 12 constitutes a hot water discharge path from the hot water storage tank 5 to the water faucet 3 together with the hot water discharge pipe 8 for discharging the hot water from the electric water heater 1 to the water faucet 3. The hot water outlet 18 is provided at the bottom 6 a of the casing 6 and receives connection of the upstream end of the hot water piping 8. That is, the hot water outlet 18 constitutes a connection portion between the hot water pipe 12 in the casing 6 and the hot water piping 8 outside the casing 6 in the hot water discharge path from the hot water storage tank 5 to the faucet 3.

  The drain pipe 13 connects the hot water storage tank 5 and a drain port 19 communicating with the atmosphere. That is, one end (upstream end) of the drain pipe 13 is connected to a predetermined location of the hot water storage tank 5 and communicates with the inside of the hot water storage tank 5, and the other end (downstream end) of the drain pipe 13 is Connected to the drain 19 and opened to the atmosphere. In the present embodiment, the upstream side of the drain pipe 13 is connected to the top surface portion 5 c of the hot water storage tank 5, and the downstream side of the drain pipe 13 is extended from the bottom 6 a side of the casing 6 to the outside of the casing 6. It is connected to a drain port 19 provided outside.

  The drain pipe 13 has a piping configuration for discharging water that overflows due to volume expansion or the like in the hot water storage tank 5 having a sealed structure. For this reason, the drain pipe 13 is provided with a relief valve 20 that automatically opens and closes according to the tank pressure.

  The relief valve 20 is configured to keep the tank pressure below a predetermined pressure together with the pressure reducing valve 17 so that the tank pressure does not become an excessive pressure, and the tank pressure is set to a predetermined pressure (for example, , 0.1 MPa), a pressure relief valve (safety valve) that automatically opens to release water in the hot water storage tank 5 and closes automatically as the tank pressure drops. That is, as the automatic opening / closing operation according to the tank pressure, the relief valve 20 is closed when the tank pressure received from the upstream side of the drain pipe 13 is less than a predetermined pressure, and the tank pressure is set to a predetermined value. The valve opens and closes when the pressure is exceeded. The relief valve 20 has a well-known configuration, for example, having a valve body portion such as a diaphragm that opens and closes when the tank pressure varies.

  Moreover, in the electric water heater 1 of this embodiment, a part of the water supplied to the water supply pipe 11 from a water supply source is used as the water discharged from the faucet 3. For this reason, the electric water heater 1 includes a water discharge pipe 21 that branches from the water supply pipe 11 and guides part of the water from the water supply source to the faucet 3.

  As shown in FIG. 2, the water discharge pipe 21 is piped in the casing 6, is branched from the downstream side of the check valve 16 of the water supply pipe 11, and is connected to a water outlet 22 that communicates with the water tap 3. In the present embodiment, the water discharge pipe 21 branches from the downstream side of the valve unit 15 in the water supply pipe 11, that is, further downstream of the pressure reducing valve 17 provided on the downstream side of the check valve 16. Accordingly, one end (upstream end portion) of the water discharge pipe 21 communicates with a portion downstream of the valve unit 15 of the water supply pipe 11, and the other end (downstream end portion) of the water discharge pipe 21 is a water outlet. 22 is connected.

  Thus, the water discharge pipe 21 is a pipe that branches water from the water supply source passing through the water supply pipe 11 and leads it to the water outlet 22. That is, the water discharge pipe 21 discharges water from the hot water storage tank 5 to the water faucet 3 while forming a water discharge path from the water supply pipe 11 to the water faucet 3 together with the water discharge pipe 9 for discharging water from the electric water heater 1 to the water faucet 3. Configure part of the path. The water outlet 22 is provided at the bottom 6 a of the casing 6 and receives connection of the upstream end of the water outlet pipe 9. That is, the water outlet 22 constitutes a connecting portion between the water outlet pipe 21 in the casing 6 and the water outlet pipe 9 outside the casing 6 in the water outlet path from the water supply pipe 11 to the faucet 3.

  In the electric water heater 1 as described above, the stored water in the hot water storage tank 5 can be used when the water supply from the water supply source to the hot water storage tank 5 is stopped, such as in the event of an unexpected water outage or a disaster. Done. Since the electric water heater 1 of this embodiment uses the water in the hot water storage tank 5 at the time of a water supply stop, it is equipped with the following structures. That is, as described above, a water discharge pipe 21 that branches a part of the water supplied from the water supply source to the hot water storage tank 5 and leads it to the faucet 3, and an air introduction pipe 23 provided with a negative pressure valve 30 in the middle. (See FIG. 2). Here, the negative pressure valve 30 is a valve mechanism that performs an automatic opening / closing operation according to the tank pressure and functions as an air introduction valve for the hot water storage tank 5.

  The air introduction pipe 23 extends from the hot water storage tank 5 and is piped in the casing 6 to open the hot water storage tank 5 to the atmosphere. That is, one end (downstream end) of the air introduction pipe 23 is connected to the hot water storage tank 5 and communicates with the hot water storage tank 5, and the other end (upstream end) of the air introduction pipe 23 is connected to the casing 6. It extends outside and is open to the atmosphere.

  In the present embodiment, one end side of the atmosphere introduction pipe 23 is connected to the top surface part 5 c of the hot water storage tank 5, and the other end side of the atmosphere introduction pipe 23 extends from the bottom part 6 a side of the casing 6 to the outside of the casing 6. ing. The atmosphere introduction pipe 23 may be any one that opens the inside of the hot water storage tank 5 to the atmosphere, and therefore, a portion where one end side of the air introduction pipe 23 is connected to the hot water storage tank 5, and other parts of the air introduction pipe 23 The position where the end side extends out of the casing 6 is not particularly limited. Therefore, one end side of the air introduction pipe 23 may be connected to, for example, the bottom 5a of the hot water storage tank 5, the side face part, and the like, and the other end side of the air introduction pipe 23 is, for example, the top surface part of the casing 6 or You may extend from a side part and you may open in the inside of the casing 6. FIG.

  The air introduction pipe 23 has a piping configuration for introducing the atmosphere into the hot water storage tank 5 when the inside of the hot water storage tank 5 having a sealed structure becomes negative pressure. For this reason, the air introduction pipe 23 is provided with a negative pressure valve 30 that operates when the inside of the hot water storage tank 5 becomes negative pressure.

  The negative pressure valve 30 is configured to introduce air into the hot water storage tank 5 when the inside of the hot water storage tank 5 having a sealed structure becomes negative pressure, and automatically when the internal pressure of the hot water storage tank 5 becomes negative pressure. This is a valve mechanism that opens and introduces air into the hot water storage tank 5 and automatically closes as the tank pressure increases. That is, the negative pressure valve 30 is closed automatically when the tank pressure is higher than atmospheric pressure, and is opened when the tank pressure is lower than atmospheric pressure, that is, negative pressure, as an automatic opening / closing operation according to the tank pressure. Open / close operation is performed. The negative pressure valve 30 has, for example, a valve body that is urged in the valve closing direction by an elastic member such as a spring and opens the valve against the urging of the elastic member when the inside of the hot water storage tank 5 becomes negative pressure. It is a thing of the structure.

  An example of the configuration of the negative pressure valve 30 will be described with reference to FIG. As shown in FIG. 3A, the negative pressure valve 30 is provided in a state of being housed in a substantially cylindrical joint member 24 that constitutes the atmosphere introduction pipe 23. The joint member 24 includes an atmosphere-side opening 24a that opens to the side that is open to the atmosphere (the lower side in FIG. 3A), and a hot water storage tank 5 side (in FIG. And a tank-side opening 24b that opens upward. That is, in the atmosphere introduction pipe 23, one end of a pipe constituting a portion on the atmosphere opening side of the atmosphere introduction pipe 23 is connected to the atmosphere side opening 24 a of the joint member 24, and the tank side opening 24 b of the joint member 24 is connected. Is connected to one end of a pipe constituting a portion of the air introduction pipe 23 on the hot water storage tank 5 side. Therefore, when the atmosphere is introduced into the hot water storage tank 5 by the atmosphere introduction pipe 23, the atmosphere flows from the atmosphere side opening 24 a side to the tank side opening 24 b side in the joint member 24.

  The substantially cylindrical joint member 24 is substantially at a position closer to the upstream side (lower side in FIG. 3A) in the interior thereof with respect to the cylinder axis direction of the joint member 24 (vertical direction in FIG. 3A). It has a vertical support wall 24c. The negative pressure valve 30 is supported on the tank side opening 24b side of the support wall 24c.

  As shown in FIG. 3A, the negative pressure valve 30 houses a spherical valve body 32 in a substantially cylindrical valve casing 31. The valve casing 31 is open on both sides in the cylinder axis direction. One opening is an intake side opening 31a on the air introduction side (upstream side), and the other opening is a side that discharges air. Let it be the exhaust side opening 31b on the (downstream side). That is, the negative pressure valve 30 is provided with respect to the joint member 24 such that the intake side opening 31a faces the atmosphere side opening 24a and the exhaust side opening 31b faces the tank side opening 24b. Here, the negative pressure valve 30 has a protruding opening 31c that forms a reduced diameter portion of the valve casing 31 and forms the intake side opening 31a at the end on the intake side opening 31a side, and this protruding opening 31c. Is supported through the support wall 24c from the downstream side to the upstream side. The negative pressure valve 30 is provided inside the joint member 24 in a state where a portion of the valve casing 31 is fixed to the joint member 24 by, for example, screwing or welding.

  In the negative pressure valve 30, a valve seat on which the valve body 32 is seated is constituted by an O-ring 33 provided in the storage space 31 d of the valve body 32 inside the valve casing 31. The O-ring 33 is provided in a state of being positioned by a wall surface that forms the storage space 31 d of the valve casing 31 so that the center axis direction coincides with the cylinder axis direction of the valve casing 31. In such a negative pressure valve 30, the negative pressure valve 30 is closed by the valve body 32 being in pressure contact with the O ring 33 so as to block one side (downstream side) of the O ring 33. When the valve body 32 is separated from the O-ring 33, the negative pressure valve 30 is opened.

  The valve body 32 is provided movably in the cylinder axis direction of the valve casing 31 on the downstream side of the O-ring 33 in the storage space 31 d of the valve casing 31. The valve body 32 is provided in a state of being biased in a direction in which it is pressed against the O-ring 33 by a coil spring 34 as an elastic member provided in the storage space 31d. That is, the coil spring 34 is provided on the side opposite to the O-ring 33 side (downstream side) with respect to the valve body 32, and one end side (downstream side) is supported by the wall surface forming the storage space 31 d of the valve casing 31. At the same time, the valve body 32 is pressed and biased in a state where the other end side (upstream side) is in contact with the valve body 32. The valve body 32 is a member made of synthetic resin such as rubber or metal.

  On the other hand, in the valve casing 31, on the side opposite to the O-ring 33 side of the valve body 32, that is, on the downstream side, a flow path forming member 35 that forms an air flow path when the negative pressure valve 30 is open is provided. . The flow path forming member 35 is a substantially cylindrical member that is open at both ends, and is open inside the valve casing 31 so that the opening end on one end projects into the storage space 31d and the opening on the other end. It is provided in a state where it is positioned and fixed so that the portion faces the exhaust opening 31b.

  The flow path forming member 35 supports the valve body 32 moved to the downstream side against the urging force of the coil spring 34 by the opening end portion on one end side thereof. That is, the valve body 32 moves against the urging force of the coil spring 34 and comes into contact with one end of the flow path forming member 35, so that the upstream opening end of the flow path forming member 35 is the valve body. It becomes a mode closed by 32. Thus, in order to ensure the air flow path from the storage space 31d to the exhaust side opening 31b in the state where the valve body 32 is in contact with one end of the flow path forming member 35, the flow path forming member 35 The slit part 35a is formed.

  The slit part 35a is formed along the longitudinal direction (cylinder axis direction) of the flow path forming member 35 so as to cut out a part of the circumferential direction in the cylindrical flow path forming member 35. Therefore, the cross-sectional shape of the flow path forming member 35 is a substantially C shape in which a position corresponding to the slit portion 35a is cut out in a substantially annular shape. Due to the presence of the slit portion 35a, the flow path forming member 35 communicates between the storage space 31d and the exhaust side opening portion 31b in a state where the upstream opening end is closed by the valve body 32. Ensure state. A downstream portion of the coil spring 34 is externally fitted to the protruding portion of the flow path forming member 35 with respect to the storage space 31d.

  The negative pressure valve 30 configured as described above performs the following automatic opening / closing operation in accordance with the tank pressure. As shown to Fig.3 (a), the negative pressure valve 30 will be in the closed state, when a tank pressure is more than atmospheric pressure. That is, when the negative pressure valve 30 is closed, the valve body 32 is pressed against the O-ring 33 by the urging force of the coil spring 34 and is seated, and between the intake side opening 31a and the exhaust side opening 31b. Communication is cut off. According to such a closed state of the negative pressure valve 30, the introduction of the atmosphere into the hot water storage tank 5 is blocked in the atmosphere introduction pipe 23.

  On the other hand, when the tank pressure is less than atmospheric pressure, that is, negative pressure, the negative pressure valve 30 is opened as shown in FIG. That is, in the open state of the negative pressure valve 30, the valve element 32 is separated from the O-ring 33 against the biasing force of the coil spring 34, and the space between the intake side opening 31a and the exhaust side opening 31b is between. It becomes a state of communication. According to such a valve open state of the negative pressure valve 30, introduction of the atmosphere into the hot water storage tank 5 by the atmosphere introduction pipe 23 is allowed. In the negative pressure valve 30 in the open state, from the intake side opening 31a facing the atmosphere side opening 24a, through the gap between the O-ring 33 and the valve body 32, the storage space 31d and the inside of the flow path forming member 35 An air flow path is formed through the passage to the exhaust side opening 31b that opens toward the tank side opening 24b (see arrow A1). When the tank pressure returns to atmospheric pressure or higher, the valve element 32 is seated on the O-ring 33 by the urging force of the coil spring 34, and the negative pressure valve 30 is closed.

  Thus, the negative pressure valve 30 opens when the inside of the hot water storage tank 5 becomes negative pressure, and permits the introduction of the atmosphere into the hot water storage tank 5 by the air introduction pipe 23 whose one end is open to the atmosphere. Note that the configuration shown in FIG. 3 is only an example of the negative pressure valve 30, and the automatic opening / closing operation according to the tank pressure as described above, that is, when the tank pressure is equal to or higher than the atmospheric pressure, the valve is closed. A specific configuration for realizing the opening / closing operation is not particularly limited as long as it is an automatic opening / closing operation that opens when the pressure is less than atmospheric pressure.

  As described above, the configuration including the air introduction pipe 23 communicating with the inside of the hot water storage tank 5 and extending from the hot water storage tank 5 and the negative pressure valve 30 provided thereon has the air introduction in the electric water heater 1 of the present embodiment. Functions as a means. That is, the configuration including the air introduction pipe 23 and the negative pressure valve 30 is connected to the hot water storage tank 5 and functions as a means for introducing the air into the hot water storage tank 5 when the tank pressure is less than atmospheric pressure.

  As described above, the electric water heater 1 according to the present embodiment includes the water discharge pipe 21, the air introduction pipe 23, and the negative pressure valve 30 as a configuration for using the water in the hot water storage tank 5 when the water supply is stopped. This is advantageous when water in the hot water storage tank 5 is used. This will be specifically described.

  In the electric water heater 1 that adopts the first-stop type configuration, the hot water storage tank 5 has a sealed structure. Therefore, when the water in the hot water storage tank 5 is discharged using its own weight when the water supply is stopped, the hot water storage tank It is necessary to introduce air into the interior 5. Therefore, the electric water heater 1 of this embodiment includes an air introduction pipe 23 provided with a negative pressure valve 30 as air introduction means for introducing air into the hot water storage tank 5. As a result, the negative pressure in the hot water storage tank 5 becomes negative as described above, so that the negative pressure valve 30 is opened and the air is automatically introduced into the hot water storage tank 5 by the atmospheric air introduction pipe 23.

  On the other hand, in order to use the water in the hot water storage tank 5, a water discharge path for discharging the water in the hot water storage tank 5 to the outside is required. In particular, when discharging water using the weight of water in the hot water storage tank 5, it is necessary to provide the water discharge path below the hot water storage tank 5. Therefore, the electric water heater 1 of the present embodiment branches from the middle of the water supply pipe 11 disposed below the bottom 5a of the hot water storage tank 5 in the casing 6 and guides water to the faucet 3 at the water outlet 22. A drain pipe 21 connected to the drain pipe 9 is provided. As a result, from the hot water storage tank 5 to the faucet 3, a pipe portion closer to the hot water storage tank 5 than the branch position of the water discharge pipe 21 of the water supply pipe 11, the water discharge pipe 21 branched from the water supply pipe 11, the water discharge pipe 21 and the water tap The water discharge path for discharging water to the outside by the head pressure in the hot water storage tank 5 is constituted by the water discharge pipe 9 communicated with 3. That is, the hot water storage tank 5 and the faucet 3 existing at a position lower than the bottom portion 5a of the hot water storage tank 5 are connected to each other through this water discharge path.

  In the configuration as described above, when the water supply is stopped, the water tap 3 to which one end of the water discharge pipe 9 is connected performs water discharge operation so that the water in the hot water storage tank 5 is below the hot water storage tank 5 as described above. The water discharge path tends to flow out by its own weight (by head pressure), and a negative pressure is generated in the hot water storage tank 5. When the inside of the hot water storage tank 5 becomes negative pressure, the negative pressure valve 30 is opened, and the air is automatically introduced into the hot water storage tank 5 through the air introduction pipe 23 and water is discharged from the water discharge path. Specifically, water in the hot water storage tank 5 is discharged from the mixing plug 3c by performing a water discharge operation with the operation handle 3d of the water tap 3 (see FIG. 1).

  Therefore, regarding the water discharge from the water faucet 3 in the hot water storage tank 5 at the time of such a water supply stop, the water discharge amount is adjusted and stopped by the operation of the operation handle 3d as in the case of the normal water discharge operation. Is called. That is, the water discharge path from the water supply source to the faucet 3 and the water discharge path from the hot water storage tank 5 to the faucet 3 in a state where the water supply from the water supply source to the hot water storage tank 5 is alive are connected to the faucet 3. In order to make the piping common to the outlet pipe 21, the water discharge amount of the water in the hot water storage tank 5 when the water supply is stopped is also controlled by operating the operation handle 3d for performing the normal water discharge operation in the faucet 3. It becomes possible to adjust and stop. Then, the water discharge in the hot water storage tank 5 by the operation of the faucet 3 is basically performed as long as the head pressure is obtained in the hot water storage tank 5, that is, until the water in the hot water storage tank 5 is almost exhausted.

  As described above, the electric water heater 1 according to the present embodiment includes the water discharge pipe 21, the air introduction pipe 23, and the negative pressure valve 30 as described above, so that when the water supply to the hot water storage tank 5 is stopped, A water discharge path to the stopper 3 is secured, and the water in the hot water storage tank 5 can be used.

  According to the electric water heater 1 of the present embodiment having the above-described configuration, when the water supply to the hot water storage tank 5 is stopped, the amount of water in the hot water storage tank 5 can be discharged by an easy operation. That is, according to the electric water heater 1 of the present embodiment, the faucet such as the operation of the operation handle 3d as described above in the case of an emergency in which water supply from the water supply source is stopped due to, for example, an unexpected water outage or a disaster. 3, the water in the hot water storage tank 5 can be discharged by a normal water discharge operation. Thereby, when using the water in the hot water storage tank 5 at the time of a water supply stop, water can be easily sprinkled by usual operation, and usability can be improved. In addition, since the operation for discharging the water in the hot water storage tank 5 at the time of stopping the water supply is a familiar operation as usual, it is possible to perform a fine adjustment as usual for the adjustment and stoppage of the water discharge amount. An appropriate amount of water can be taken out as required. This makes it possible to effectively use the water in the hot water storage tank 5 until there is no water in the hot water storage tank 5 without wasting water in the hot water storage tank 5. Further, since the water in the hot water storage tank 5 can be discharged by operating the faucet 3, even when the water in the hot water storage tank 5 is taken out before the temperature of the water in the hot water storage tank 5 is lowered, The operation part for taking out the water in the hot water storage tank 5 is heated by the hot water in the hot water storage tank 5 and the operation becomes difficult, and the trouble such as inadvertently receiving the hot water and feeling uncomfortable is avoided. be able to.

  In particular, in the electric water heater 1 of the present embodiment, since the water discharge in the hot water storage tank 5 when the water supply is stopped is performed by the configuration including the negative pressure valve 30, the hot water storage tank 5 is operated by operating the faucet 3 as usual. A state in which the water in the inside can be taken out can be automatically realized. That is, in the electric water heater 1 of the present embodiment, as described above, a negative pressure is generated in the hot water storage tank 5 by the water discharge operation by the faucet 3 in a state where water supply from the water supply source to the hot water storage tank 5 is stopped. Thus, the negative pressure valve 30 is opened, the atmosphere is automatically introduced into the hot water storage tank 5 and water is discharged from the faucet 3. For this reason, for example, the electric water heater 1 is automatically connected to the faucet 3 when the water supply is stopped without requiring any special operation such as operation of an emergency drain valve built in the casing for storing the hot water storage tank. By this operation, the water in the hot water storage tank 5 can be taken out.

  Specifically, as a conventional hot water storage type electric water heater, for example, having a drain stop valve for draining water in the hot water storage tank when cleaning the hot water storage tank or replacing water in the hot water storage tank There is. This drain stop cock is often provided inside an electric water heater, for example, in a state of being covered with a cover so as not to open carelessly. In such a configuration in which the drain stop cock is provided inside the electric water heater, it is necessary to remove the cover and the like covering the valve when operating the valve for opening and closing the drain stop cock. The operation for operating the water stop cock is very complicated. In this regard, according to the electric water heater 1 of the present embodiment, when the water supply is stopped, no special operation is required as described above, and the water in the hot water storage tank 5 is taken out by operating the faucet 3 as usual. It is possible to automatically realize a state where it is possible. That is, even when the water supply is stopped, the water in the hot water storage tank 5 can be used only by operating the faucet 3 as usual. Therefore, in the electric water heater 1, the water in the hot water storage tank 5 is used when the water supply is stopped. At this time, it is possible to obtain a state that is extremely easy to use without taking time and effort.

[Second Embodiment]
A second embodiment of the present invention will be described. In addition, about the content which is common in 1st Embodiment, description is abbreviate | omitted suitably using the code | symbol common to 1st Embodiment. Although the electric water heater 201 according to the present embodiment is common to the electric water heater 1 according to the first embodiment in that a negative pressure valve is provided as a configuration for using the water in the hot water storage tank 5 when water supply is stopped. The negative pressure valve is provided in the drain pipe 13 provided with the relief valve, and the negative pressure valve is provided as an integral valve unit together with the relief valve.

  As shown in FIG. 4, the electric water heater 201 of the present embodiment is configured to use the water in the hot water storage tank 5 when the water supply is stopped in comparison with the electric water heater 1 of the first embodiment shown in FIG. 2. In this regard, in place of the air introduction pipe 23 having the negative pressure valve 30, the drain pipe 13 for discharging water overflowing the hot water storage tank 5 due to volume expansion or the like is provided with a valve unit 40 including the function of the negative pressure valve. The valve unit 40 has a negative pressure valve function and a relief valve function.

  The configuration of the valve unit 40 will be described with reference to FIG. The valve unit 40 includes a main body 41 and an operation lever 42 provided on one end side of the main body 41. The valve unit 40 is interposed at a substantially right-angled corner portion in the piping configuration of the drain pipe 13. For this reason, the main body portion 41 includes an inlet portion 43 to which one end side of a pipe arranged in the first direction (vertical direction in FIG. 5) is connected in communication, and a second that is substantially perpendicular to the first direction. And one outlet side of the piping arranged in the direction (left and right direction in FIG. 5). The inflow port 43 is connected to a pipe constituting a portion of the drain pipe 13 closer to the drain port 19 than the valve unit 40. The outflow port 44 is connected to the hot water storage tank 5 side of the drain pipe 13 from the valve unit 40. Are connected.

  The main body 41 has a first cylindrical body 45 that forms the inlet 43 and the outlet 44, and a substantially cylindrical shape that projects from the first body 45 along the direction facing the inlet 43. And a second body 46. The inside of the main body 41 is partitioned into a first chamber 47 where the inflow port portion 43 faces and a second chamber 48 where the outflow port portion 44 faces. The first chamber 47 and the second chamber 48 are mainly constituted by the first body. The valve unit 40 includes a relief valve 50 and a negative pressure valve 60 as a valve mechanism that switches between a communication state and a non-communication state between the first chamber and the second chamber by an opening / closing operation.

  First, the relief valve 50 will be described. The relief valve 50 is mainly configured in the second body 46. The relief valve 50 is a diaphragm valve 51 as a valve body, an operation shaft 52 provided along the central axis direction of the diaphragm valve 51, and engages with the operation shaft 52 in an energized state and supports the diaphragm valve 51. And a coil spring 54 that urges the urging support plate 53.

  The diaphragm valve 51 is a valve provided as a part of a first partition part 45 a provided in the first body 45 so as to partition the first chamber 47 and the second chamber 48 on the side facing the inlet part 43. The seat 55 is seated from the side opposite to the inlet 43 side (upper side in FIG. 5). The first partition wall 45a is formed with a flow passage hole 45b that allows the first chamber 47 and the second chamber 48 to communicate with each other, and the wall surface on the second chamber 48 side (the upper side in FIG. 5) of the first partition wall 45a. The valve seat 55 is provided as a circumferential protrusion along the shape of the flow path hole 45b.

  The diaphragm valve 51 includes a diaphragm 56 made of an elastic material such as rubber, a valve base 57 that supports the diaphragm 56, and a crimping member 58 that caulks and fixes the diaphragm 56 and the valve base 57 to each other. The diaphragm 56 is an integral member having a substantially disk-like outer shape as a whole. The diaphragm 56 includes a disk-like base portion 56 a that forms a portion that contacts the valve seat 55 in a state where the diaphragm valve 51 is seated, and the diaphragm valve 51. It has an annular support part 56b for supporting in the main body part 41, and a connecting part 56c which is a part connecting the base part 56a and the support part 56b.

  The valve base 57 is a member configured in a bottomed cylindrical shape, and the diaphragm 56 is placed in a state where the bottom 57 a side is in contact with the base portion 56 a of the diaphragm 56 from the side opposite to the valve seat 55 side with respect to the diaphragm 56. To support.

  The caulking member 58 fixes the base portion 56 a of the diaphragm 56 to the bottom portion 57 a of the valve base 57. Specifically, the caulking member 58 is caulked in a central position with respect to the bottom portion 57a of the valve base 57 and the base portion 56a of the diaphragm 56 in a state of being overlapped with each other, whereby the diaphragm 56 and the valve base 57 are Are fixed to each other. One side (lower side in FIG. 5) of the caulking member 58 penetrating the bottom portion 57a of the valve base 57 and the base portion 56a of the diaphragm 56 faces the first chamber 47 side, and the other side (upper side in FIG. 5) It faces the substrate 57.

  The diaphragm valve 51 is supported in a state where the base portion 56 a of the diaphragm 56 is opposed to the valve seat 55 inside the main body portion 41 and the annular support portion 56 b of the diaphragm 56 is fixed to the main body portion 41. Here, the support portion 56b of the diaphragm 56 is fixed to the main body portion 41 in a state of being sandwiched between flange portions 45c and 46c formed at the joint portions of the first body 45 and the second body 46. The

  The diaphragm valve 51 having such a configuration includes a base portion 56a of the diaphragm 56, a valve base 57, and a caulking member 58 by utilizing elastic deformation of the connecting portion 56c between the base portion 56a of the diaphragm 56 and the support portion 56b. The portions are integrally reciprocated in the direction in which the base portion 56a approaches and separates from the valve seat 55 (vertical direction in FIG. 5). The relief valve 50 is closed or opened by the reciprocating operation of the diaphragm valve 51.

  The relief valve 50 is closed when the diaphragm valve 51 is seated with the base portion 56a of the diaphragm 56 being pressed against the valve seat 55. In the closed state of the relief valve 50, the flow passage hole 45b of the first partition wall portion 45a is closed from the second chamber 48 side, and the first chamber 47 and the second partition wall 45a are in the portion of the first partition wall portion 45a. The chamber 48 is not in communication. The urging force for pressing the diaphragm valve 51 against the valve seat 55 includes the elastic force of the connecting portion 56 c of the diaphragm 56.

  On the other hand, the relief valve 50 is opened when the diaphragm valve 51 separates the base portion 56a of the diaphragm 56 away from the valve seat 55. In the open state of the relief valve 50, the flow passage hole 45b of the first partition wall portion 45a is opened, and the first chamber 47 and the second chamber 48 are in communication with each other at the first partition wall portion 45a. Become.

  The operation shaft 52 is a substantially rod-like member as a whole, and is provided so that its longitudinal direction is along the cylinder axis direction of the substantially cylindrical second body 46 and is movable in the longitudinal direction. The operating shaft 52 has one end (the lower side in FIG. 5) inserted into the caulking member 58 of the diaphragm valve 51, and the other end (the upper side in FIG. 5) the end of the substantially cylindrical second body 46. The end surface portion 46 a is penetrated and protruded outside the main body portion 41. The operating shaft 52 has a main body portion 52a that is a rod-shaped portion having a constant diameter, and a locking end portion 52b that is provided at an end portion of the main body portion 52a on the diaphragm valve 51 side. The locking end portion 52b forms an enlarged diameter portion with respect to the main body portion 52a from the main body portion 52a side to the front end side, and forms a reduced diameter portion thinner than the main body portion 52a on the front end side. The operating shaft 52 inserts the reduced diameter portion of the locking end portion 52 b into a support hole 58 a formed in the crimping member 58.

  The urging support plate 53 is a dish-like member having a flange 53a formed at the edge of the substantially bowl-shaped main body. In other words, the urging support plate 53 is a member having a substantially hat shape by the substantially bowl-shaped main body part and the collar part 53a. The urging support plate 53 has an operating shaft 52 at the bottom (substantially hat-shaped top surface) 53b of the substantially bowl-shaped main body while the flange 53a side is directed to the diaphragm valve 51 (lower side in FIG. 5). Provided in a penetrating state. In this way, the urging support plate 53 that penetrates the operating shaft 52 locks the portion of the bottom 53b to the step formed between the main shaft 52a and the enlarged diameter portion of the operating shaft 52 by the locking end 52b. The operation shaft 52 is supported by the operation shaft 52 in a state where the movement of the operation shaft 52 toward the distal end side (the lower side in FIG. 5) is restricted relative to the operation shaft 52.

  The coil spring 54 is provided in a state of penetrating the operating shaft 52, and biases the operating shaft 52 toward the diaphragm valve 51 (lower side in FIG. 5) via the biasing support plate 53. One end (diaphragm valve 51 side) end of the coil spring 54 is supported by the flange 53a of the urging support plate 53 that is locked to the operating shaft 52 as described above. On the other hand, the other end of the coil spring 54 (on the end surface portion 46a side of the second body 46) is supported by the spring receiving member 59 inside the end surface portion 46a of the second body 46 (inside the main body portion 41). Is done. The spring receiving member 59 is a plate-like member provided substantially parallel to the end surface portion 46 a in a state of being fixed to the second body 46. The spring receiving member 59 has a projection 59 a for positioning the coil spring 54 by fitting the end of the coil spring 54 on the plate surface on the side supporting the coil spring 54. The spring receiving member 59 and the end surface portion 46a of the second body 46 allow the operating shaft 52 to pass therethrough while allowing movement in the axial direction thereof.

  As described above, the coil spring 54 is biased and supported by biasing the biasing support plate 53 toward the diaphragm valve 51 in a state where one end side is supported with respect to the spring receiving member 59 fixed to the second body 46. The operating shaft 52 to which the plate 53 is locked is indirectly biased toward the diaphragm valve 51 side. The coil spring 54 urges the operating shaft 52 via the urging support plate 53, thereby causing the diaphragm valve 51 to receive insertion of the distal end portion of the locking end portion 52 b of the operating shaft 52 by the caulking member 58. The valve is biased in the valve closing direction (lower side in FIG. 5).

  The operation lever 42 provided for the main body 41 configured as described above is an operation unit that is manually operated, and is configured to switch the state of the relief valve 50 between the following two states. . That is, two states of an automatic open / close state as a first state in which an automatic open / close operation according to the tank pressure is performed and an open state as a second state in which the valve opened state is maintained regardless of the tank pressure. It is. That is, the relief valve 50 has two states, an automatic open / close state and an open state, as states that can be switched to each other by manual operation.

  As shown in FIG. 5, the operating lever 42 is rotatably supported with respect to the operating shaft 52 by a shaft support portion 42 a at a protruding portion of the operating shaft 52 from the main body 41. The operation lever 42 is a linear member, and is supported by the shaft support portion 42a at a position offset to one side in the longitudinal direction. In the operation lever 42, the long side portion of the operation lever 42 starting from the support position by the shaft support portion 42a in the longitudinal direction becomes the grip portion 42b.

  As shown in FIG. 5, when the relief valve 50 is automatically opened and closed, the operation lever 42 is supported in a state in which the operation lever 42 faces the vertical direction with respect to the operating shaft 52. The automatic open / close relief valve 50 is a drain pipe 13 that is a piping configuration for discharging water overflowing due to volume expansion or the like in the hot water storage tank 5 having a sealed structure, and the relief valve 20 in the electric water heater 1 of the first embodiment. It has the same function.

  That is, the relief valve 50 is configured to keep the tank pressure below a predetermined pressure together with the pressure reducing valve 17 so that the tank pressure does not become an excessive pressure, and the tank pressure is set to a predetermined pressure. It is a pressure relief valve (safety valve) having a structure that automatically opens when the pressure rises (for example, 0.1 MPa) to release water in the hot water storage tank 5 and automatically closes as the tank pressure decreases. Accordingly, the relief valve 50 performs an opening / closing operation according to the tank pressure, which is closed when the tank pressure is lower than a predetermined pressure and opened when the tank pressure is higher than the predetermined pressure.

  Specifically, in the relief valve 50, the diaphragm in a state of being seated on the valve seat 55 by the above-described predetermined pressure acting from the outlet portion 44 side communicating with the hot water storage tank 5, that is, the second chamber 48 side. The valve 51 moves away from the valve seat 55 against the urging force of the coupling portion 56c of the diaphragm 56 and the coil spring 54, and the relief valve 50 is opened. The diaphragm valve 51 moves the operating shaft 52 and the urging support plate 53 in which the distal end portion is inserted into the caulking member 58 against the urging force of the coil spring 54 with the separation from the valve seat 55. As a result, the second chamber 48 and the first chamber 47 communicate with each other via the first partition wall 45a, and the excessive pressure in the hot water storage tank 5 causes the second chamber 48, the inlet, where the outlet 44 faces. It escapes from the drain port 19 through the first chamber 47 facing the portion 43 and the downstream side of the valve unit 40 of the drain pipe 13. Here, the water overflowing the hot water storage tank 5 due to volume expansion or the like is discharged from the drain port 19 through the valve unit 40 by the drain pipe 13.

  When the pressure acting on the relief valve 50 is lower than the predetermined pressure from the open state of the relief valve 50 in the automatic opening / closing state, the diaphragm valve 51 is attached by the connecting portion 56c of the diaphragm 56 and the coil spring 54. The valve seat 55 is seated by the force, and the relief valve 50 is closed. Thereby, in the part of the 1st partition part 45a, the 2nd chamber 48 and the 1st chamber 47 will be in a non-communication state.

  The state of the relief valve 50 is switched from the automatic opening / closing state in which the automatic opening / closing operation is performed according to the tank pressure as described above to the open state by the operation of the operation lever 42. Specifically, in the automatic opening / closing state of the relief valve 50, the operation lever 42 is supported in a state in which it is oriented in the vertical direction with respect to the operating shaft 52 as described above. The operation lever 42 in this state is rotated about 90 ° about the shaft support portion 42a until the longitudinal direction substantially coincides with the longitudinal direction of the operating shaft 52. Here, the operation lever 42 is operated to rotate in a direction in which the tip on the side of the gripping portion 42b moves away from the main body 41 from the shaft support 42a (see arrow B1 in FIG. 5).

  The open state of the relief valve 50 is used in the electric water heater 201 to drain water in the hot water storage tank 5 when, for example, cleaning the hot water storage tank 5 or replacing water in the hot water storage tank 5. That is, the relief valve 50 is in an automatic open / close state during normal use of the electric water heater 201, and switching to the open state by operating the operation lever 42 is unusually performed when cleaning the hot water storage tank 5 or the like. Done.

  Next, the negative pressure valve 60 will be described. The negative pressure valve 60 according to the present embodiment has the same configuration as the negative pressure valve 30 according to the first embodiment (see FIGS. 3A and 3B). That is, the negative pressure valve 60 is configured to introduce the atmosphere into the hot water storage tank 5 when the inside of the hot water storage tank 5 having a sealed structure becomes negative pressure, similarly to the negative pressure valve 30 of the first embodiment. This is a valve mechanism having a structure that automatically opens when the inside of the tank 5 becomes negative pressure, introduces air into the hot water storage tank 5, and automatically closes as the tank pressure increases. Therefore, the negative pressure valve 60 is closed automatically when the tank pressure is equal to or higher than the atmospheric pressure, and is opened when the tank pressure is lower than the atmospheric pressure, that is, when the pressure is negative, as an automatic opening / closing operation according to the tank pressure. Open / close operation is performed. In addition, about the specific structure of the negative pressure valve 60, the code | symbol same as the negative pressure valve 30 of 1st Embodiment is attached | subjected, and description is abbreviate | omitted.

  As shown in FIG. 5, in the present embodiment, the negative pressure valve 60 is provided in the second chamber 48 in the main body 41. The negative pressure valve 60 is provided on the second chamber 48 side with respect to the second partition wall portion 45d provided so as to partition the first chamber 47 and the second chamber 48 on the side facing the outflow port portion 44 in the first body 45. It is supported and fixed to the first body 45.

  In the second chamber 48, the negative pressure valve 60 is arranged such that the intake side opening 31 a faces the first chamber 47 through the second partition wall 45 d and the exhaust side opening 31 b flows in the second chamber 48. It is provided so as to face the outlet 44. Here, the negative pressure valve 60 is supported in a state in which the projecting opening 31c is passed through the second partition wall 45d from the second chamber 48 side to the first chamber 47 side. The negative pressure valve 60 is provided inside the second chamber 48 in a state where a portion of the valve casing 31 is fixed to the first body 45 by, for example, screwing or welding.

  As described above, in the electric water heater 201 of the present embodiment including the valve unit 40 having the relief valve 50 and the negative pressure valve 60 in the drain pipe 13, the automatic opening / closing state of the relief valve 50, which is a normal use state (FIG. 5). In reference), the negative pressure valve 60 automatically operates according to the tank pressure. In the automatic opening / closing state of the relief valve 50, the relief valve 50 is in a closed state unless the tank pressure becomes equal to or higher than a predetermined pressure, and between the first chamber 47 and the second chamber 48 on the first partition wall portion 45a side. The non-communication state is maintained.

  And the negative pressure valve 60 will be in the closed state, when a tank pressure is more than atmospheric pressure (refer Fig.3 (a)). According to such a closed state of the negative pressure valve 60, the first chamber 47 and the second chamber 48 on the second partition wall portion 45d side are not in communication with each other, and the atmosphere of the hot water storage tank 5 in the drain pipe 13 is disconnected. Installation is blocked.

  On the other hand, when the tank pressure is less than atmospheric pressure, that is, negative pressure, the negative pressure valve 60 is opened (see FIG. 3B). According to such an open state of the negative pressure valve 60, introduction of the atmosphere into the hot water storage tank 5 by the drain pipe 13 is allowed. Specifically, when the negative pressure valve 60 is opened, the air introduced into the drain pipe 13 from the drain port 19 is transferred from the inlet 43 to the first chamber 47 and the first chamber in the valve unit 40. 47 through the intake side opening 31a, the clearance between the O-ring 33 and the valve body 32, the storage space 31d, the passage in the flow path forming member 35, and the exhaust side opening 31b, the second chamber 48 and the second chamber. An atmospheric flow path is formed through a route from 48 to the outlet 44 (see arrow C1 in FIG. 5). And if a tank pressure returns to atmospheric pressure or more, the negative pressure valve 60 will be in a valve closing state.

  As described above, in the electric water heater 201 according to the present embodiment, the negative pressure valve 60 is opened by the negative pressure in the hot water storage tank 5 in the automatic opening / closing state of the relief valve 50, and the drain valve 19 is connected to one end. Allows the introduction of the atmosphere into the hot water storage tank 5 through the drain pipe 13 opened to the atmosphere. Therefore, in the electric water heater 201 of the present embodiment, the negative pressure valve 60 provided in the drain pipe 13 is closed when the tank pressure is equal to or higher than atmospheric pressure, and opened when the tank pressure is lower than atmospheric pressure. Functions as air introduction means. In other words, in the present embodiment, the negative pressure valve 60 provided in the drain pipe 13 is connected to the hot water storage tank 5 by the drain pipe 13 so that the atmosphere is introduced into the hot water storage tank 5 when the tank pressure is less than atmospheric pressure. It functions as a means.

  According to the electric water heater 201 of the present embodiment as described above, in the automatic opening / closing state of the relief valve 50, when the water supply to the hot water storage tank 5 is stopped, as with the electric water heater 1 of the first embodiment, for example, the operation handle By operating the faucet 3 such as 3d (see FIG. 1), the water in the hot water storage tank 5 can be discharged from the faucet 3 by the head pressure of the hot water storage tank 5. That is, the negative pressure valve 60 is opened by the negative pressure in the hot water storage tank 5 due to the water discharge operation at the faucet 3, the atmosphere is automatically introduced into the hot water storage tank 5 by the drain pipe 13, and the drain pipe 21 is configured. Water is discharged from the water discharge path.

  On the other hand, in the electric water heater 201 of the present embodiment, in the open state of the relief valve 50, when the water discharge operation of the faucet 3 is performed when the water supply to the hot water storage tank 5 is stopped, the hot water storage tank 5 in the valve unit 40 is entered. The atmospheric air introduction path is a path opened by opening the relief valve 50. That is, in this case, in the valve unit 40, the flow from the inlet 43 to the first chamber 47 and the first partition 45a with respect to the path through the negative pressure valve 60 as described above (see arrow C1 in FIG. 5). The route of the outlet portion 44 is given priority through the passage hole 45 b and the second chamber 48. In other words, in the electric water heater 201 of the present embodiment, the negative pressure valve 60 basically does not operate even when a negative pressure is generated in the hot water storage tank 5 when the relief valve 50 is open.

  As described above, the electric water heater 201 of the present embodiment includes the relief valve 50 and the negative pressure valve 60 provided in the drain pipe 21 and the drain pipe 13 as described above, so that when the water supply to the hot water storage tank 5 is stopped. A water discharge path from the hot water storage tank 5 to the faucet 3 is secured, and the water in the hot water storage tank 5 can be used. That is, according to the electric water heater 201 of the present embodiment, the negative pressure valve 60 can automatically obtain a state in which the water in the hot water storage tank 5 can be used by operating the faucet 3 when the relief valve 50 is automatically opened and closed. In addition, the state in which the water in the hot water storage tank 5 can be used by the operation of the faucet 3 can also be obtained by opening the relief valve 50 by the operation of the operation lever 42.

  According to the electric water heater 201 of the present embodiment having the above-described configuration, the water in the hot water storage tank 5 is required by an easy operation when the water supply to the hot water storage tank 5 is stopped as in the case of the first embodiment. It is possible to discharge the water by an appropriate amount, and it is possible to avoid problems in the case where the water in the hot water storage tank 5 is taken out before the temperature of the water in the hot water storage tank 5 decreases.

  In addition, in the automatic open / close state of the relief valve 50 that is a normal use state of the electric water heater 201, the water discharge in the hot water storage tank 5 when the water supply to the hot water storage tank 5 is stopped corresponds to the tank pressure of the negative pressure valve 60. Since it is performed by the opening / closing operation, it is possible to automatically realize a state in which water in the hot water storage tank 5 can be taken out by operating the faucet 3 as usual. Therefore, regarding the use of the water in the hot water storage tank 5 when the water supply is stopped, the relief valve 50 may not be configured to be manually operable by the operation lever 42 or the like.

  However, like the electric water heater 201 of the present embodiment, the relief valve 50 is provided with a configuration that can be opened by operating the operation lever 42, so that the negative pressure valve 60 is not activated for some reason when the water supply is stopped. Even if it exists, the state which can take out the water in the hot water storage tank 5 by operation of the water tap 3 can be obtained by operating the operation lever 42 manually and opening the relief valve 50. FIG. Thereby, the state which can take out the water in the hot water storage tank 5 by operation of the faucet 3 at the time of a water supply stop can be ensured reliably. That is, from the viewpoint of ensuring that the water in the hot water storage tank 5 can be used in an emergency such as when the water supply is stopped, the relief valve 50 is operated by operating the operation lever 42 as in the electric water heater 201 of the present embodiment. It can be said that the structure which can be made into an open state is preferable.

  Moreover, in the electric water heater 201 of this embodiment, the negative pressure valve 60 included in the configuration for using the water in the hot water storage tank 5 when the water supply is stopped is provided in the drain pipe 13 having the relief valve 50. . For this reason, according to the electric water heater 201 of the present embodiment, in the comparison with the electric water heater 1 of the first embodiment, when a negative pressure valve is provided as the air introduction means, the configuration corresponding to the air introduction pipe 23 is omitted. Therefore, the configuration for using the water in the hot water storage tank 5 when the water supply is stopped can be realized with a simple configuration.

  Further, in the electric water heater 201 of the present embodiment, the relief valve 50 and the negative pressure valve 60 are provided as a valve unit 40 that is connected to the middle part of the drain pipe 13. That is, the relief valve 50 and the negative pressure valve 60 are provided in a state of being housed in an integral member of the main body portion 41 having the inlet portion 43 and the outlet portion 44 as a pipe connection portion in the drainage pipe 13, Use a common pipe connection.

  According to such a configuration, the piping configuration can be simplified when the relief valve 50 and the negative pressure valve 60 are provided in the drain pipe 13. Further, since the relief valve 50 and the negative pressure valve 60 can be integrally removed as the valve unit 40, maintenance and replacement of the relief valve 50 and the negative pressure valve 60 can be easily performed.

[Third Embodiment]
A third embodiment of the present invention will be described. In addition, about the content which is common in 1st Embodiment and 2nd Embodiment, description is abbreviate | omitted suitably using the same code | symbol as these embodiments. The electric water heater 301 according to the present embodiment is different from the electric water heater 201 according to the second embodiment in that the negative pressure valve 60 is omitted.

  As shown in FIG. 6, the electric water heater 301 of this embodiment is a structure for using the water in the hot water storage tank 5 at the time of a water supply stop in contrast with the electric water heater 201 of 2nd Embodiment shown in FIG. In this regard, instead of the valve unit 40 having the relief valve 50 and the negative pressure valve 60, a manually operable relief valve 70 is provided in the drain pipe 13.

  The relief valve 70 will be described with reference to FIGS. The relief valve 70 according to the present embodiment has the same configuration as the relief valve 50 according to the second embodiment (see FIG. 5). That is, the relief valve 70 has an automatic open / close state and an open state as states that can be switched by operating the operation lever 42 as in the case of the relief valve 50 of the second embodiment. 17 functions as a pressure relief valve (safety valve) for keeping the tank pressure below a predetermined pressure. That is, the relief valve 70 is provided in the drain pipe 13, and in the automatic open / close state, the relief valve 70 is closed when the tank pressure is lower than a predetermined pressure, and is opened when the tank pressure is higher than the predetermined pressure. Open and close in response. In addition, about the specific structure of the relief valve 70, the code | symbol same as the relief valve 50 of 2nd Embodiment is attached | subjected, and description is abbreviate | omitted.

  In the example shown in FIGS. 7 and 8, the relief valve 70 is provided in the same manner as the relief valve 50 in a configuration in which the negative pressure valve 60 is omitted from the valve unit 40 of the second embodiment. Therefore, as in the case shown in FIG. 5, in the automatic opening / closing state of the relief valve 70 as shown in FIG. 7, the relief valve 70 performs an automatic opening / closing operation according to the tank pressure, so that the drain pipe 13 The communication state / non-communication state of the first chamber 47 communicating with the drain port 19 side and the second chamber 48 communicating with the hot water storage tank 5 side is switched. Further, the relief valve 70 is switched from the automatic open / close state to the open state by the operation of the operation lever 42. In the open state of the relief valve 70, the relief valve 70 maintains the opened state regardless of the tank pressure. . In this embodiment, since the negative pressure valve 60 in the second embodiment is omitted, the communication state / non-communication state between the first chamber 47 and the second chamber 48 is the opening / closing operation of the relief valve 70. Can only be switched. FIG. 8 shows an open state of the relief valve 70.

  Here, switching of the state of the relief valve 70 by the operation lever 42 will be described in detail. As shown in FIG. 7, in the automatic opening / closing state of the relief valve 70, the operation lever 42 is supported in a state in which it is oriented in the vertical direction with respect to the operating shaft 52. As shown in FIG. 8, the operation lever 42 in this state is rotated about 90 ° around the shaft support portion 42 a until the longitudinal direction substantially coincides with the longitudinal direction of the operating shaft 52. Here, the operation lever 42 is operated to rotate in a direction in which the tip on the grip portion 42b side of the shaft support portion 42a is away from the main body portion 41 (see arrow D1 in FIG. 8).

  When the operation lever 42 is rotated in this manner, the side opposite to the gripping portion 42b from the shaft support portion 42a of the operation lever 42, that is, the short side starting from the support position by the shaft support portion 42a in the longitudinal direction of the operation lever 42. The end surface portion 46a of the second body 46 is pressed by the pressing portion 42c which is the portion of the second body 46. As the reaction of the pressing of the end surface portion 46a by the pressing portion 42c accompanying the rotation of the operating lever 42, the operating shaft 52 to which the operating lever 42 is connected is pulled out in the protruding direction from the end surface portion 46a. That is, the pressing portion 42c comes into contact with the end surface portion 46a in the process in which the operating lever 42 in a state of being perpendicular to the operating shaft 52 is operated, and the operating shaft 42 is further rotated from this state, whereby the operating shaft 52 is moved. Pulled out. Therefore, in the operation lever 42, the length, shape, and the like of the pressing portion 42c are set so that the end surface portion 46a is pressed by the rotation and a desired movement amount is obtained with respect to the operating shaft 52. Hereinafter, the movement in the direction in which the operating shaft 52 is pulled out (upward in FIGS. 7 and 8) is assumed to be an increase.

  As the operation shaft 52 is raised by the turning operation of the operation lever 42, the urging support plate 53 that is locked to the operation shaft 52 as described above is also raised integrally with the operation shaft 52. That is, the operating shaft 52 rises against the urging force by the coil spring 54 received through the urging support plate 53. In the process in which the operating shaft 52 is raised by the turning operation of the operation lever 42, the biasing support plate 53 interferes with the valve base 57 constituting the diaphragm valve 51 and raises the diaphragm valve 51.

  Here, in order to receive the engagement from the urging support plate 53, the valve base 57 has an engagement piece portion 57b protruding inward in a bottomed cylindrical shape. The engagement piece portion 57b is a protruding piece portion formed by bending a part of the peripheral wall portion inward in the bottomed cylindrical valve base 57, for example. The engagement piece portion 57b is disposed on the upper side of the flange portion 53a of the urging support plate 53 (upper side in FIGS. 7 and 8) while avoiding interference with the coil spring 54 contacting the flange portion 53a. It is provided so as to partially overlap the collar portion 53a in a direction view. Thus, the urging support plate 53 is engaged with the diaphragm valve 51 as the operating shaft 52 is raised by the engaging piece portion 57b while engaging with the operating shaft 52 at the locking end portion 52b. Match.

  With respect to the rise of the diaphragm valve 51 due to the turning operation of the operation lever 42, the diaphragm valve 51 is at least released regardless of the tank pressure, that is, even when the hot water storage tank 5 is less than the predetermined pressure as described above. The valve 70 is raised to a position where the valve 70 is open (separated from the valve seat 55). The state in which the operation lever 42 is rotated in this way (see FIG. 8) is held by a biasing force or the like with respect to the operating shaft 52 via the biasing support plate 53 by the coil spring 54. Thus, the state in which the diaphragm valve 51 is held at the position separated from the valve seat 55 regardless of the tank pressure is the open state of the relief valve 70.

  As described above, in the electric water heater 301 of this embodiment, the relief valve 70 is switched from the automatic open / close state to the open state by the operation of the operation lever 42, so that one end is opened to the atmosphere by the drain port 19. The introduction of air into the hot water storage tank 5 through the drain pipe 13 is allowed. Therefore, in the electric water heater 301 of the present embodiment, the configuration including the drain pipe 13 and the open relief valve 70 functions as the air introduction means. That is, in this embodiment, the relief valve 70 provided in the drain pipe 13 is opened by operating the operation lever 42, so that the atmosphere is introduced into the hot water storage tank 5 when the tank pressure is less than atmospheric pressure. Function as a means for

  According to the electric water heater 301 of the present embodiment as described above, when the water supply to the hot water storage tank 5 is stopped, the relief valve 70 is switched to the open state by operating the operation lever 42, for example, the operation handle 3d (see FIG. 1). The operation of the faucet 3 such as the operation of) enables the water in the hot water storage tank 5 to be discharged from the faucet 3 by the head pressure of the hot water storage tank 5. That is, when the inside of the hot water storage tank 5 becomes negative pressure by the water discharge operation at the faucet 3, air is introduced into the hot water storage tank 5 through the relief valve 70 by the drain pipe 13 and the drain pipe 21 is configured. Water is discharged from the water discharge path. Here, as shown in FIG. 8, the introduction path of the atmosphere in the relief valve 70 is similar to the case where the relief valve 50 of the electric water heater 201 of the second embodiment is in the open state from the inlet 43 to the first chamber. 47, a path (see arrow E1 in FIG. 8) reaching the outflow port 44 via the flow passage hole 45b of the first partition wall 45a and the second chamber 48.

  As described above, the electric water heater 301 according to the present embodiment includes the water discharge pipe 21, the drain pipe 13, and the relief valve 70 as described above, so that when the water supply to the hot water storage tank 5 is stopped, the water tap 3 It is possible to secure a water discharge route to the water and use the water in the hot water storage tank 5. That is, according to the electric water heater 301 of the present embodiment, the water in the hot water storage tank 5 can be used by operating the faucet 3 by manually operating the operation lever 42 to open the relief valve 70. A state is obtained.

  According to the electric water heater 301 of the present embodiment having the above-described configuration, the water in the hot water storage tank 5 is required by an easy operation when the water supply to the hot water storage tank 5 is stopped as in the case of the first embodiment. It is possible to discharge the water by an appropriate amount, and it is possible to avoid problems in the case where the water in the hot water storage tank 5 is taken out before the temperature of the water in the hot water storage tank 5 decreases.

  In addition, according to the electric water heater 301 of the present embodiment, when the water in the hot water storage tank 5 is used when the water supply is stopped, the configuration of the relief valve 70 is used. The existing structure of the relief valve provided in the can be used. Moreover, since it is not necessary to provide the negative pressure valve or the like as described above as a configuration for using the water in the hot water storage tank 5 when the water supply is stopped, the configuration can be simplified correspondingly. In addition, when water supply is stopped, a state in which the water in the hot water storage tank 5 can be used by the operation of the faucet 3 can be reliably obtained by the manual operation of the operation lever 42.

  In the embodiment of the present invention described above, the so-called wall-mounted electric water heater has been described as an example. However, the electric water heater according to the present invention is not limited to the wall-mounted electric water heater. The electric water heater according to the present invention stores a hot water storage tank provided with heating means for heating water in a casing, and provides a flow path of water discharged from the hot water storage tank at a position lower than the bottom of the hot water storage tank outside the casing. The configuration is not particularly limited as long as it is a front-end type electric water heater that opens and closes by a water faucet.

1 Electric water heater (front-end electric water heater)
3 Water faucet 5 Hot water storage tank 5a Bottom 5b Heater (heating means)
5c Top surface part 6 Casing 11 Water supply pipe 12 Hot water discharge pipe 13 Drainage pipe 14 Water supply port 16 Check valve 18 Hot water outlet 19 Drainage port 21 Drainage pipe 22 Drainage outlet 23 Atmospheric introduction pipe 30 Negative pressure valve 40 Valve unit 50 Relief valve 60 Negative pressure valve 70 Relief valve 201 Electric water heater (first stop electric water heater)
301 Electric water heater (front-end electric water heater)

Claims (3)

A hot water storage tank provided with heating means for heating water is housed in a casing, and a flow path of water from the hot water storage tank is opened and closed by a faucet provided at a position lower than the bottom of the hot water storage tank outside the casing. A first-stop electric water heater,
A water supply pipe connecting the water supply port provided in the casing and the bottom of the hot water storage tank, and supplying water to the hot water storage tank;
A check valve provided in the water supply pipe;
Connecting the top surface of the hot water storage tank and a hot water outlet provided in the casing and communicating with the faucet, and a hot water outlet pipe for guiding water in the hot water storage tank to the hot water outlet;
A water outlet pipe branched from the downstream side of the check valve of the water supply pipe and connected to a water outlet connected to the water tap;
A drain pipe connecting the hot water storage tank and a drain port communicating with the atmosphere;
An air introduction means connected to the hot water storage tank and introducing air into the hot water storage tank when the pressure in the hot water storage tank is less than atmospheric pressure. The air introduction means is a negative pressure valve that is provided in the drain pipe and closes when the pressure in the hot water storage tank is equal to or higher than atmospheric pressure, and opens when the pressure in the hot water storage tank is lower than atmospheric pressure. The tip-stop electric water heater according to claim 1. A pressure in the hot water storage tank that is provided in the drain pipe and is closed when the pressure in the hot water storage tank is lower than a predetermined pressure, and is opened when the pressure in the hot water storage tank is equal to or higher than the predetermined pressure. Further equipped with a relief valve that opens and closes according to
The relief valves are in a state in which they are switched to each other by manual operation, and a first state in which an opening / closing operation is performed according to the pressure in the hot water storage tank and a state in which the valve is opened regardless of the pressure in the hot water storage tank are held. Two states,
The front-end type electric water heater according to claim 1, wherein the air introduction means includes the drain pipe and the relief valve in the second state.

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